1. Field of the Invention
This invention relates to selected silylamines which are useful, particularly as scavengers, in Group Transfer Polymerization.
2. Background
U.S. Pat. Nos. 4,414,372; 4,417,034; 4,508,880; 4,524,196; 4,581,428; 4,588,795; 4,598,161; 4,605,716; 4,622,372; 4,656,233; 4,681,918; and 4,711,942; and commonly assigned U.S. patent application Ser. No. 004,831 filed Jan. 13, 1987, referred to hereinafter as "the aforesaid patents and patent applications", disclose processes for polymerizing an acrylic or maleimide monomer to a "living" polymer in the presence of:
(i) an initiator having at least one initiating site and which is a tetracoordinate organo(Si, Sn or Ge) compound, including such compound having at least one oxygen, nitrogen or sulfur atom attached to the Si, Sn or Ge; and
(ii) a co-catalyst which is a source of fluoride, bifluoride, cyanide or azide ions or a suitable Lewis acid, Lewis base or selected oxyanion. Such polymerization processes have become known in the art as Group Transfer Polymerization (Webster et al., "Group Transfer Polymerization--A New and Versatile Kind of Addition Polymerization", J. Am. Chem. Soc. 105, 5706 (1983)).
Preferred monomers for use in Group Transfer Polymerization are selected from acrylic and maleimide monomers of the formula CH.sub.2 .dbd.C(Y)X and ##STR1## and mixtures thereof, wherein:
X is --CN, --CH.dbd.CHC(O)X' or --C(O)X'; PA0 Y is --H, --CH.sub.3, --CN or --CO.sub.2 R, provided, however, when X is --CH.dbd.CHC(O)X', Y is --H or --CH.sub.3 ; PA0 X' is --OSi(R.sup.1).sub.3, --R, --OR or --NR'R"; PA0 each R.sup.1, independently, is a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms or --H, provided that at least one R.sup.1 group is not --H; PA0 R is: PA0 each of R' and R" is independently selected from C.sub.1-4 alkyl. PA0 each Q', independently, is selected from --OR.sup.1, --SR.sup.1, --N(R.sup.1).sub.2 and --R.sup.1 ; PA0 Z is an activating substituent selected from the group consisting of ##STR2## --SR.sup.6, --OP(NR'R").sub.2, --OP(OR.sup.1).sub.2, --OP[OSi(R.sup.1).sub.3 ].sub.2 and mixtures thereof; PA0 X.sup.2 is --OSi(R.sup.1).sub.3, --R.sup.6, --OR.sup.6 or --NR'R"; PA0 R.sup.6 is PA0 each of R.sup.2 and R.sup.3 is independently selected from --H and a hydrocarbyl or polymeric radical, defined as for R.sup.6 above, subparagraphs (a) to (e); PA0 R', R", R.sup.1 and Z' are as defined above for the monomer; PA0 m is 2, 3 or 4; PA0 n is 3, 4 or 5; PA0 Z.sup.1 is ##STR3## wherein X.sup.2, R.sup.2 and R.sup.3 are as defined above; R.sup.2 and R.sup.3 taken together are ##STR4## provided Z is ##STR5## X.sup.2 and either R.sup.2 or R.sup.3 taken together are ##STR6## provided Z is ##STR7## and M is Si, Sn, or Ge. PA0 X.sup.1 is ##STR9## provided, however, when the monomer is a nitrile, X.sup.1 is ##STR10## each R.sup.4, independently, is: (a) a C.sub.1-12 alkyl, C.sub.4-12 cycloalkyl, C.sub.6-12 aralkyl or di(C.sub.1-4 alkyl)amino group; PA0 each R.sup.5 is --CH.sub.2 CH.sub.2 -- or --CH.sub.2 CH.sub.2 -- containing one or more alkyl or other substituents that are unreactive under polymerizing conditions. PA0 R.sup.1 is alkyl, alkylether, alkylester, alkylketene, alkylcyano or aralkyl; PA0 R.sup.2 is hydrocarbyl or a moiety selected from Si, O, S, N, P, C, B, Sn, Pb, Ca, hydrazine, azo, CO, CO.sub.2, organic peroxides and metal oxides; PA0 X is a hydrolyzable leaving group selected from amido, amino, carbamato, enoxy, imidato, isocyanato, oximato, thioisocyanato and ureido radicals; PA0 a is 1-4; PA0 b is 0 or 1-3; PA0 c is 0 or 1-3; PA0 4-(a+b+c) is 0 or 1-3. PA0 X.sup.3 is --H or C.sub.1-12 n-alkyl; PA0 Y.sup.1 is --H, C.sub.1-12 n-alkyl, aryl or alkaryl; PA0 a is 1, 2 or 3; PA0 b is 0 or 1; PA0 c is 1 or 2; PA0 (a+b+c) is 4; PA0 X.sup.3 and Y.sup.1 taken together with --N&lt; form a 5- or 6-membered saturated heterocyclic ring or a 5- or 6-membered heterocyclic ring containing one or more substituents that are inert under polymerizing conditions; PA0 each Z.sup.2, independently, is C.sub.1-2 alkylene; PA0 a' and b' are defined as for a and b, respectively; and PA0 (a'+b') is 3. PA0 GPC: gel permeation chromatography PA0 M.sub.n : number average molecular weight (via GPC) PA0 M.sub.w : weight average molecular weight (via GPC) PA0 MMA: methyl methacrylate PA0 MTS: [(1-methoxy-2-methyl-1-propenyl)oxy]trimethylsilane PA0 MWD: M.sub.w /M.sub.n PA0 PMMA: poly(methyl methacrylate) PA0 TAS: a 1 molar solution of tris(dimethylamino)sulfonium bifluoride in acetonitrile PA0 THF: tetrahydrofuran
(a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA1 (b) a polymeric radical containing at least 20 carbon atoms; PA1 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA1 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA1 (e) a radical of (a), (b), (c) or (d) containing one or more reactive substituents of the formula --Z'(O)C--C(Y.sup.1).dbd.CH.sub.2 wherein Y.sup.1 is --H or --CH.sub.3 and Z' is O or NR' wherein R' is as defined below; and PA1 (a) a hydrocarbyl radical which is an aliphatic, alicyclic, aromatic or mixed aliphatic-aromatic radical containing up to 20 carbon atoms; PA1 (b) a polymeric radical containing at least 20 carbon atoms; PA1 (c) a radical of (a) or (b) containing one or more ether oxygen atoms within aliphatic segments thereof; PA1 (d) a radical of (a), (b) or (c) containing one or more functional substituents that are unreactive under polymerizing conditions; or PA1 (e) a radical of (a), (b), (c) or (d) containing one or more initiating sites; PA1 (b) a group of (a) wherein two or three of the alkyl, cycloalkyl and/or aralkyl groups are joined together by means of one or more carbon-carbon bonds; PA1 (c) a group of (a) or (b) wherein the alkyl, cycloalkyl and/or aralkyl groups contain within aliphatic segments thereof one or more hetero atoms selected from O, N and S; or PA1 (d) a group of (a), (b) or (c) wherein the alkyl, cycloalkyl and/or aralkyl groups contain one or more substituents that are unreactive under polymerizing conditions; and
Preferred initiators are selected from tetracoordinate organsilicon, organotin and organogermanium compounds which may be represented by the formulas Q.sub.3 'MZ, Q.sub.2 'M(Z.sup.1).sub.2 and [Z.sup.1 (Q').sub.2 M].sub.2 O
wherein:
Preferred initiators are those wherein M is Si.
Preferred co-catalysts are selected from a source of bifluoride ions HF.sub.2.sup.- ; a source of fluoride, cyanide or azide ions; a source of oxyanions, said oxyanions being capable of forming a conjugate acid having a pKa (DMSO) of about 5 to about 24; a suitable Lewis acid, for example, zinc chloride, bromide or iodide, boron trifluoride, an alkylaluminum oxide or an alkylaluminum chloride; or a suitable Lewis base, for example, a Lewis base of the formula selected from (R.sup.4).sub.3 M' and ##STR8## wherein: M' is P or As;
Additional details regarding Group Transfer Polymerization can be obtained from the aforesaid patents and patent applications, the disclosures of which are hereby incorporated by reference.
U.S. Pat. Nos. 4,489,191; 4,499,229; 4,503,209 and 4,539,367 disclose selected silanes, including silylamines, as scavengers of hydroxy functional materials in moisture-curable silicone room temperature vulcanizable (RTV) compositions. For example, '191 discloses silane scavengers of the formula EQU (R.sup.1 O).sub.4-(a+b+c) --Si(R.sup.2).sub.c (H).sub.a (X).sub.b
wherein:
It is an object of this invention to provide selected silylamines which can be used, particularly as scavengers, in Group Transfer Polymerization. Another object is to provide silylamines which are not deleterious to Group Transfer Polymerization or to the polymer produced thereby and which can be added directly to the polymerization reaction mixture or, alternatively, can be used to treat and/or purify the reactants and other ingredients employed in Group Transfer Polymerization. These and other objects will become apparent hereinafter.
Commonly assigned U.S. patent application Ser. No. 044,881 discloses the use of some of the silylamines described herein as initiators of (meth)acrylate polymerization. It is to be understood that the invention herein is considered separate and distinct from any invention disclosed and claimed in the commonly assigned application, about which more will be discussed hereinafter.